Electricity Saving Tips For Homes And Offices

Split or Window which air conditioner should you buy?

By on May 1, 2017

Should I buy a split air conditioner or a window air conditioner? This is a question that many air conditioner buyers thinks of, before making a purchase. And we keep getting this question quite regularly at Bijli Bachao. It is not just about split or window, but about a whole lot of things that should be considered while buying an air conditioner.  Air Conditioner is an appliance that can significantly blow up your electricity bills and utmost care should be taken while buying one. With this article we would try to provide you some guidelines on things to take care of before making a purchase decision for an air conditioner. Please note an air conditioner bought once will go on for next 10 years at least and thus it is important to make a right decision.

Split vs Window

Buying a split or a window is something that worries a lot of people. But from energy efficiency perspective there is no preferred choice. Both split and window can be equally efficient. What matters is EER or Energy Efficiency Ratio of the air conditioner. EER represents the amount of cooling an air conditioner can provide per watt of electricity it consumes. Bureau of Energy Efficiency rates air conditioners on its star rating based on EER of air conditioners. Higher the EER of air conditioner higher the star rating it will have. So a 5 star rated air conditioner provides more cooling per watt of electricity used.

Both split and window can have high EER ratios. But it is observed that Split air conditioners have more number of models in BEE 5 star rating as compared to Window air conditioners (check our research on air conditioners at this link: link). So if you are looking for high efficiency air conditioners then split air conditioners can provide you more options.

The main difference between the two is that window air conditioner has a single unit whereas split air conditioner has 2 units (indoor and outdoor). Split is lot more silent in operation as compared to window and looks aesthetically pleasing, but is relatively more complicated to install and requires more space as compared to window air conditioner.

Right sizing an air conditioner is very important

The most important thing that one should figure out before buying any air conditioner is the right size of the air conditioner. This can significantly impact your electricity bills. And from size we mean tonnage of air conditioner. Every room that is cooled has a certain amount of heat that depends on:

  1. Size of the room. This determines the amount of air in the room that needs to be cooled.
  2. Number of people in the room. Every human being emits heat and air conditioner needs to cool it.
  3. Amount of stuff kept in the room. Please note every item kept in the room will get cooled from the air conditioner, so lesser the stuff, lesser the electricity air conditioner will consume.
  4. Number of electrical appliances in the room (most electrical appliances emit heat, especially lights). Incandescent light bulbs can increase cooling load.
  5. Windows in the room. More the windows, more is the heat coming from outside. Well-insulated windows reduce cooling load. Check our insulation section for more details: https://www.bijlibachao.com/Save-Electricity/Insulation/
  6. Walls facing the sun can increase cooling load. Touch your walls and windows to check if they are hot or not and using the tips in insulation section to prevent heating of the room.

The amount of heat in a room and that coming in from walls and windows is represented in BTU (or British Thermal Unit). BTU is sum of heat from all the above-mentioned sources.




Every air conditioner has a cooling capacity, which is represented in BTU/hr. It is the BTUs of heat that it can remove in an hour. If the heat coming in the room (in BTUs) is more than the heat that air conditioner can remove, then the air conditioner will not be as effective. Thus an undersized air conditioner cannot remove heat effectively and the compressor of the air conditioner will continue running all the time thereby consuming more electricity.

With an undersized air conditioner, the compressor will keep running all the time and the temperature will not reach the desired level. They will not only be ineffective in cooling, but will also consume more electricity.

An oversized air conditioner will not only over cool your room but also will be ineffective in removing the humidity in a room. So if you set AC to 25, the extra energy that the compressor provides will cool it beyond 25. It will have shorter run cycles but all air conditioners are designed for optimum run cycles and if the cycle is shorter than that then the efficiency is reduced (source: energy star).

So every air conditioner is designed to run at optimum efficiency only if it is used as per the right size. So always size the air conditioner properly. You can use the calculator available at this link before buying an air conditioner: http://www.lg.com/in/support/ac-tonnage-calculator.

If you are not sure about what size to buy, you can always buy an inverter technology air conditioner, as it adjusts to the size and requirements of the room automatically, and thus makes optimum electricity consumption. To check more about inverter ac see our article: Air Conditioners with Inverter technology can help save electricity.

Look for the right options in the air conditioner

In a previous article (Various modes for running air conditioners and their impact on electricity bill) we discussed about various modes of air conditioners and their impact on electricity consumption. It is very important to figure out if the air conditioner has all the modes as per your requirement. If you live in humid area, a dry mode is important. Any air conditioner with energy saver mode and features should be preferred.

Star rating is for real

BEE Star rating of air conditioner does matter a lot. Any air conditioner would consume anywhere between 1-2 units per hour of usage based on tonnage, efficiency and size. Which means if it is used for 10 hours per day, it can consume about 10-20 units in a day or 300-600 units a month (for 10 hours of use daily). At an average rate of Rs 6-7 per unit (you can check your per unit rate using our calculator: Online Electricity Bill Calculator – For all states in India) it can be close to Rs 1800-4000 per month. If your usage is high then the yearly cost of an air conditioner can go very high. In case of high usage, incremental cost of buying a higher star rated air conditioner can easily be recovered in a few years. Please note that the air conditioner will work for at least 10 years and the electricity prices are on a rise. Buying an efficient one while buying a new air conditioner can prevent a lot of heartburn for you in future.

It is important to make a right decision while buying an air conditioner, as it is a long-term utility for you. Do not let lucrative deals, discounts and persuasion by a sales person impact your decision to buy an efficient appliance. A wrong decision on an appliance like air conditioner can significantly impact your electricity bills. We are trying to work out a calculator that can help you choose the right air conditioner for you and hope to release it soon. Till that time you can check the list of top ten most efficient air conditioners at: Top Ten Air Conditioners in India by electricity consumption and size.

Here is a short video for tips to buy the best air conditioner in India

 

 

 

Check this link to see Top Ten Air Conditioners in India for Electricity Savings: http://wp.me/p4hAhQ-4I

 

References

http://www.energystar.gov/ia/home_improvement/home_sealing/RightSized_AirCondFS_2005.pdf

http://www.energystar.gov/index.cfm?c=roomac.pr_properly_sized

About the Author:
Abhishek Jain is an Alumnus of IIT Bombay with almost 10 years of experience in corporate before starting Bijli Bachao in 2012. His passion for solving problems moved him towards Energy Sector and he is keen to learn about customer behavior towards Energy and find ways to influence the same towards Sustainability. .

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